This invention relates generally to fertilizer mixtures of synthetic organic and inorganic materials and particularly to formulations containing monopotassium phosphate, ureaformaldehyde and a polyamino acid to form dry homogeneous, low burn, high analysis fertilizers which may be carried in liquid for application in surface and subsurface spraying and injection fertilization.
The use of fertilizer blends of both organic and inorganic material has become recognized as being advantageous in many fertilizer applications. Such blends not only supply nutrients which may be immediately absorbed into the plant root system, but also provide a source of long-term nutrient supply.
In order for any nutrient material to be absorbed by a plant root system, it must be dissolved to create various ion structures or salts which are readily attracted and absorbed into the root tissue by an ion exchange process. The conventional inorganic fertilizer material which may include phosphates and potassium is soluble in water and forms ions readily when dissolved. Therefore when such fertilizers are supplied to the soil in liquid form, the nutrient ions or salts are immediately available for absorption, or, if dry inorganic fertilizers are used, the nutrient ions or salts become available as water is percolated through the soil.
Various organic fertilizers, those structures which include animal, vegetable and synthetic carbon structures, on the other hand, are advantageous in that they exhibit slower rates of decomposition. That is, organic fertilizer material ordinarily is not readily soluble in water, but only breaks down by microorganism action in the soil to release nutrient ions over a period of time and thus a single fertilizer application may supply nutrients for an extended period. Such organic materials are often referred to as slow release fertilizers.
As mentioned above, organic and inorganic fertilizers may be supplied in either soluble or insoluble form and may either be spread or sprayed onto surface areas or injected or otherwise supplied to subsurface areas. However, when using readily soluble fertilizers, one is limited to the amount of nutrients which may be effectively supplied to the soil without causing damage to plant tissues, a problem commonly referred to as plant or root burn. As the nutrients of the soluble fertilizer are readily dissolved for plant absorption, an excessive amount of salt concentration due to the number of ions released adjacent the root system, may suppress the water absorption by the roots and in some cases may extract moisture from the plant causing the plant to be subjected to a moisture deficiency. However, various fertilizer nutrients are less likely to cause root burn even when in a soluble state. Generally, the potential for causing root burn is determined by the salt index of the particular nutrient, as the greater the salt index, the greater the ion concentration in the soil. Often fertilizers contain significant quantities of high salt index ingredients which, although containing necessary nutrients, may be harmful if supplied in excessive quantities.
Insoluble fertilizers, on the other hand, must be broken down by either chemical or biodegradable action and thus the rate of salt supply may be reduced somewhat depending upon climatic and soil conditions. Also, many insoluble fertilizers having particulate material of a size to be readily blended with soluble material are generally not readily adaptable to the presently increasing use of pressure or hydraulic fertilizer injection techniques since the particle sizes of the insoluble material are not small enough to allow the fertilizer material to be injected through small-bore nozzles. In addition, soluble fertilizers readily disperse throughout the root zone with hydraulic soil injection. However, insoluble fertilizer must be ground to a particulate size small enough that it is not filtered out by the soil particles, much like sand filters out insoluble particles in a swimming pool. Otherwise, the fertilizer remains at the injection site, limiting root contact.
The possibility of root burn is further increased if high analysis fertilizers are used since a greater concentration of available nutrient ions are present. High analysis fertilizer compositions are generally viewed as those in which the total percent of the nitrogen is equal to or exceeds 20% of the overall fertilizer weight and the total percent of the nitrogen, potassium and phosphate nutrients is at least 40% of the fertilizer weight.
The use of high analysis fertilizers is often desirable for several reasons. Not only will the nutrients be supplied to the consumer in less bulk, but the amount of nutrients applied per surface or subsurface applications may be significantly increased. Again, however, as the concentration of nutrient ions is increased, the danger of root burn also increases.
In addition to their burn potential, all nutrient salts or ions are subject to leaching as water dissolves minute quantities of the fertilizer material. Such dissolved material usually moves with the water and leaches away from the area of the roots. However, all nutrients do not leach to the same degree. As an example, nitrate salts (the form of nitrogen primarily absorbed by plant roots) move with ground water and rapidly leach from the root zone while potassium is moderately leached and only a trace of phosphorus is lost. Therefore, in order to insure that a source of nitrogen is maintained in the soil, an insoluble nitrogen could be used to reduce ion loss due to leaching.
Subsurface application of fertilizers is recognized as being a highly desirable method by which to provide for the efficient and effective feeding and caring of trees, shrubs and lawns by supplying nutrients directly to the area of the plant roots. Such application has the added advantage, over surface fertilizing, of decreasing the amount of fertilizer runoff or leaching caused by the action of surface waters.
In this regard, there are generally two widely accepted methods by which fertilizers may be supplied to subsurface areas. These methods include subsurface treatment with a dry fertilizer using drill or bore hole application techniques, and the subsurface injection of a liquid type fertilizer using injection apparatus.
There are, however, particular problems associated with the subsurface application of fertilizers in either dry or liquid form, especially when considering possible plant damage, economics and labor requirements. Thus, the objective of any fertilization process is the application to the soil of an optimum quantity of various macro and/or micro nutrients to insure the proper ratio and amounts of nutrient ions necessary for plant growth and nourishment in such a manner that expenses and application time are maintained at a minimum.
Liquid injection usually is desirable over dry bore hole methods because a subsurface application of fertilizer may be made in less time and therefore at a significant reduction in total man hours. Also, the liquid injection technique disperses nutrients throughout the root area increasing root contact and, thus, absorption by the plant. Dry fertilizer in vertical holes does not disperse laterally, providing only “spot” treatments of supplemental nutrients. However, most liquid fertilizers utilize soluble nutrients which if applied at the recommended nutrient level would cause root burn as an excessive amount of ions would be present in the soil immediately after the application, thereby leading to the depletion of the root water supply, as previously discussed. In practice, therefore, liquid injection techniques have necessitated a reduction in the amount of available nutrients supplied per application. For example, if the optimum quantity of a fertilizer nutrient supply is 6 lbs. of nitrogen per 1,000 square feet of root area per year, in practice approximately ½ to 2 lbs. per 1,000 square feet could be applied without fear of damage due to the possible plant or root burn which would be caused if all the nutrients were available in a soluble form.
Bore hole applications of dry fertilizers, on the other hand, permit the use of the generally insoluble or less soluble particulate material. Currently, many dry type fertilizers contain a combination of readily available inorganic and organic nutrients and slow release long chain organic nutrients. If a fertilizer includes a long chain synthetic organic nitrogen supply, the nitrogen is released only after the carbon chain is slowly broken down by chemical and biological reaction as water seeps through the soil. Thus, with a dry fertilizer, the total nutrient supply may be applied in a single application with a significant reduction in the immediately available nutrient ions thereby reducing the possibility of plant or root burn. However, the time and cost of labor to apply dry fertilizer is greater than that of using liquid injection techniques. This is because holes must be bored or drilled around each plant to be fertilized.
Therefore, although subsurface applications of dry fertilizers are advantageous in permitting an increased nutrient supply by way of slow release nitrogen components to reduce burn potential, pressure or hydraulic injection of fertilizers is often preferred as it is a quicker and easier method by which fertilizer may be applied to subsurface areas without the extra work necessitated by more traditional drill or bore hole techniques. Hydraulic injection is also the best method for nutrient dispersal throughout the root zone.
To obtain the joint benefit of liquid injection together with short and long term nutrient release of some dry fertilizers, it is important to provide a mixture of organic and inorganic fertilizer material which, when mixed with water, forms a solution of the inorganic material and a portion of the organic material and forms a suspension of the remainder of the organic material. Normally a dry inorganic material is supplied in granular or pellet form. However, since such material dissolves readily in water, it does not clog hydraulic equipment. On the other hand, granular or pellet sized particles of some insoluble organic material are not suitable for use with hydraulic injection equipment, as the particles do not pass through the openings in conventional subsurface injection equipment. The problem is in providing a uniform blend of dry soluble and insoluble organic and soluble inorganic fertilizer components which can be injected to subsurface areas when in the presence of a liquid carrier.
Further, in mixing dry synthetic organic material such as ureaformaldehyde, or ureaform, as the requisite particle size is decreased, the more the material exhibits an ability to “flow” because of its low bulk density. That is, as the powdery organic particles are mixed with various inorganic materials in granular or pellet form, they tend to readily separate or settle through the mixture and thus the overall blend is not homogeneous or uniformly mixed. Various prior art methods for effectively dry blending insoluble organic material such as ureaform with soluble inorganic materials have necessitated that the insoluble particle size be approximately the same size as the soluble particles and therefore the insoluble material is not suitable for subsurface injection.
Therefore, to provide the market or consumer with a fertilizer having water soluble inorganic material with very fine particulate water insoluble organic material uniformly suspended therein which could be used for subsurface applications, it typically has been necessary to blend the organic and inorganic material in a solution. By wet mixing, the problem associated with dry blending may be avoided, however, shipping, packaging, consumer handling and other such problems are increased due to the necessity that the fertilizer could only be available as a liquid or slurry. Therefore, it would be desirable to dry blend the materials to reduce shipping, packaging and other such costs.